1. Field of the Invention
The present invention relates to a cooling device employed in a portable electronic such as a notebook-sized personal computer or laptop personal computer.
2. Description of the Prior Art
A notebook-sized personal computer in general comprises a built-in battery assembled within its body. As long as the electric power is supplied from the battery, the notebook-sized personal computer keeps operating even when the personal computer cannot receive the electric power from an outlet. In this case, the duration of the operation depends upon the capacity of the battery. If the power consumption at a CPU (central processing unit) can be reduced, the electric power stored in the battery can be saved, so that the duration of the operation may be extended.
The power consumption at a CPU in general depends upon the clock frequency of the CPU. As the clock frequency gets higher, the power consumption gets larger. If the CPU operates at the lower clock frequency, the power consumption can be reduced at the CPU. However, the operation of the CPU may get slower. Accordingly, it is very difficult to satisfy the conflicting demands at the same time, namely, the demand to extend the duration of the operation for the notebook-sized personal computer and the demand to accelerate the operation in the notebook-sized personal computer.
The present inventors have proposed a notebook-sized personal computer comprising a CPU which operates at a low clock frequency when it receives the electric power from a battery and at a high clock frequency when it receives the electric power from an outlet. Accordingly, when the personal computer is used at a place where an outlet is not available, the electric power stored in the battery can be saved, so that it is possible to postpone the termination to the operation of the personal computer. In addition, if the CPU is intended to accelerate its operation, the personal computer may simply be connected to an outlet. The outlet normally keeps supplying the electric power to the personal computer without a limit. The supply of the electric power from the outlet enables the CPU of the personal computer to keep operating at a high processing speed without shortening the duration of the operation.
The variation in the clock frequency of the CPU induces the variation in the calorific power at the CPU in the personal computer of the above-mentioned type. When the CPU operates at a low clock frequency, a low cooling performance may sufficiently suppress an excessive rise in temperature at the CPU. On the other hand, when the CPU operates at a high clock frequency, a higher cooling performance should be achieved to prevent an excessive rise in temperature at the CPU. Heretofore, no cooling device or method of controlling a cooling device has been accomplished to realize the cooling performance variable in response to the variation in the calorific power at the CPU.
It is accordingly an object of the present invention to provide a method of controlling a cooling device so as to change the cooling performance in response to variation in calorific power. It is also an object of the present invention to provide a cooling device suitable to such method.
According to the present invention, there is provided a method of controlling a cooling device, comprising: determining whether or not a plug of an external power supply is attached to a body of a portable electronic; and changing a cooling performance of the cooling device disposed within the body when a determination indicates attachment of the plug.
The aforementioned method is adapted to assume the variation in the calorific power generated at a power consumption circuit disposed within the body of the portable electronic on the basis of the index whether or not the plug of the stable external power supply is attached to the body of the portable electronic. Intentional change in the cooling performance of the cooling device based on such index may serve to allow the cooling performance to follow the variation in the calorific power generated at the power consumption circuit. In this method, a ventilation fan may be employed in the cooling device so as to change the cooling performance, for example.
In general, the calorific power generated at the power consumption circuit such as a CPU (central processing unit) is considered to follow the amount of power consumption. When the plug is attached or connected to the portable electronic, the stable external power supply is expected to supply the electric power to the portable electronic. A relatively larger electric power is supposed to be consumed in the portable electronic when the portable electronic receives the electric power from the external power supply. However, even when the larger electric power is consumed in the portable electronic, the electric power from the external power supply is hardly exhausted. The high cooling performance of the cooling device based on expectation of a larger calorific power is expected to reliably avoid rise in the temperature within the body of the portable electronic.
The determination may indicate the attachment of the plug when a reception of the plug in a jack is detected. If the connection between the plug and jack, or the reception of the plug in the jack, is detected, the electric power is supposed to be fed from the stable external power supply to the portable electronic. The detection can be realized with a relay switch or a transistor switch, for example. In addition, the reception of the plug may be determined when the electric power supplied from the plug is detected. Such detection may be used to confirm the electric power supplied from the stable external power supply to the portable electronic.
The aforementioned method of controlling may further comprise: setting the cooling performance at a first level when an electric power is supplied from the plug to a power consumption circuit disposed within the body; and setting the cooling performance at a second level lower than the first level when an electric power is supplied to the power consumption circuit from a battery connected to the body. The power consumption circuit assembled in the portable electronic is supposed to consume a relatively larger electric power when the electric power is supplied from the plug and consume a relatively lower electric power when the electric power is supplied from the battery. The larger power consumption is assumed to lead to a larger calorific power generated at the power consumption circuit as compared with a case where the low power consumption is achieved. The achievement of the high cooling performance, specified by the first level, when the larger calorific power is generated at the power consumption circuit, is expected to reliably avoid a rise in the temperature within the body of the portable electronic.
In addition, the aforementioned method of controlling may further comprise: setting the cooling performance at a first level when a clock frequency of a power consumption circuit is set at a first frequency; and setting the cooling performance at a second level lower than the first level when the clock frequency of the power consumption circuit is set at a second frequency lower than the first frequency. The power consumption circuit such as a CPU is normally supposed to generate a larger calorific power when the CPU operates at a higher clock frequency. The achievement of the high cooling performance, specified by the first level, when the larger calorific power is generated at the power consumption circuit, is expected to reliably avoid rise in the temperature within the body of the portable electronic. In this condition, it is preferable to set the clock frequency at the first frequency when the electric power is supplied from the plug to the portable electronic and at the second frequency when the electric power is supplied from the battery to the portable electronic.
The cooling performance may be changed over from the second level to the first level when a temperature detected within the body reaches a threshold temperature level. It is accordingly possible to avoid rise in the temperature with the high cooling performance specified by the first level even when the low cooling performance specified by the second level cannot restrain rise in the temperature enough.
In setting the cooling performance at the first level, a ventilation fan may be operated to direct airflow toward a fin receiving heat transmission from the power consumption circuit. The power consumption circuit is supposed to receive the electric power from the plug as describe above when the first level is established. The electric power from the stable external power supply is hardly exhausted, so that the power consumption at the ventilation fan fails to affect on the electric power supplied to the power consumption circuit.
In setting the cooling performance at the second level, a radiation plate may be employed to radiate heat of the power consumption circuit. The power consumption circuit is supposed to receive the electric power from the battery as described above when the second level is established. Employment of the radiation plate serves to efficiently radiate heat without consuming the electric power, so that it is possible to restrain rise in the temperature without exhausting the electric power stored in the battery.
When achieving the aforementioned method, a portable electronic may comprise: a body; a cooling device disposed within the body; and a control circuit capable of changing a cooling performance of the cooling device when a plug of an external power supply is attached to the body.
The control circuit serves to change the cooling performance of the cooling device in accordance with the index whether or not the plug is attached to the portable electronic. When the portable electronic receives an enough electric power from the stable external power supply, for example, the cooling device is intended to achieve the high cooling performance in response to the supplied electric power. Even when the larger electric power is consumed at the cooling device, the electric power from the stable external power supply is hardly exhausted. On the other hand, when a limited amount of the electric power is supplied from the battery, the power consumption can be reduced at the cooling device, so that the electric power stored in the battery can be saved. The changeover of the cooling performance may be achieved with employment of a ventilation fan, for example.
The cooling device may include a fin receiving heat transmitted from a power consumption circuit, and a ventilation fan capable of changing an amount of airflow directed to the fin. Such cooling device is adapted to increase the amount of airflow from the ventilation fan when the attachment of the plug is confirmed. On the other hand, when the plug is removed, the ventilation fan may reduce the amount of airflow. The cooling device may achieve a high cooling performance in response to the increase of the supplied electric power when the cooling device receives a sufficient amount of the electric power from the stable external power supply. Even when the larger electric power is consumed at the ventilation fan, the electric power from the stable external power supply is hardly exhausted. On the other hand, when a limited amount of the electric power is supplied from the battery, the power consumption can be reduced at the ventilation fan, so that the electric power stored in the battery can be saved.
The cooling device may further include a radiation plate radiating heat generated at the power consumption circuit. The radiation plate serves to efficiently radiate heat of the power consumption circuit without consuming the electric power. Accordingly, the radiation plate may contribute to restraint of rise in temperature without inducing the exhaustion of the electric power.
A cooling device suitable to the aforementioned control may comprise: a radiation plate disposed within a body of the portable electronic so as to radiate heat from a high temperature component; a fin disposed within the body of the portable electronic so as to receive heat from the high temperature component; and a ventilation fan disposed within the body of the portable electronic so as to generate airflow directed to the fin.
The above-described cooling device may achieve a first cooling performance with the radiation from the radiation plate and a second cooling performance with the employment of the fin and the ventilation fan in addition to the radiation plate. Moreover, the radiation plate may serve to maintain the minimum cooling performance without consuming the electric power, thereby contributing to reducing the power consumption at the ventilation fan to the utmost.
The fin preferably faces an opening defined in a housing of the body. The airflow from the ventilation fan is allowed to flow out of the body of the portable electronic through the opening after absorbing the heat of the fin. The airflow heated by the fin hardly remains within the body of the portable electronic, so that rise in the temperature may efficiently be avoided within the body of the portable.
A heat conduction component is preferably disposed between the radiation plate and the fin for distributing heat from the high temperature component to the radiation plate and the fin. The heat conduction component may serve to reliably spread the heat from the high temperature component or power consumption circuit over the radiation plate and the fin. The heat conduction component may be a heat pipe. The heat pipe may comprise a container such as a vacuumed metallic tube airtightly enclosing a volatile fluid such as water.